(A) while at the same time they have introduced some 100,000 dangerous chemical pollutants, having
(B) while at the same time introducing some 100,000 dangerous chemical pollutants that have
(C) while they have introduced some 100,000 dangerous chemical pollutants at the same time, which have
(D) but introducing some 100,000 dangerous chemical pollutants at the same time that have
(E) but at the same time introducing some 100,000 dangerous chemical pollutants, having
这道题B选项确实是最好的,但是prep解释中说“while 引导从句时,如主从句的主语一致,且从句谓语又含有 be,则从句主语和 be 可省略。while 后可直接跟现在分词、名词、形容词或介词短语。如:We are teachers while (we are) serving as students.我们边当老师边当学生”。这里我想问一下,如果是这种情况的话那么还原后应该是“while at the same time Industrialization and modern methods of insect control are introducing some 100,000 dangerous chemical pollutants that have”这里面“are introducing ”和前面的“have improved ”是不是太不平行了呢?还是说“sb do… while doing”是固定用法?那么什么情况下这么用呢?谢谢大侠指教~